
#include <stdlib.h>
#include <stdio.h>
#include <memory.h>
#include <math.h>
#include <unistd.h>
#define pi				3.14159265358979323846 
#define c				3
#define screen_width	50
#define screen_height	25
float cube[6][4][3] = {
	{
		{-0.5, -0.5,  0.5}, { 0.5, -0.5,  0.5}, {-0.5,  0.5,  0.5}, { 0.0,  0.0,  1.0}
	 },
	{
		{-0.5, -0.5,  0.5}, {-0.5, -0.5, -0.5}, {-0.5,  0.5,  0.5}, {-1.0,  0.0,  0.0}
	},
	{
		{-0.5, -0.5,  0.5}, {-0.5, -0.5, -0.5}, { 0.5, -0.5,  0.5}, { 0.0, -1.0,  0.0}
	},
	{
		{-0.5,  0.5,  0.5}, { 0.5,  0.5,  0.5}, {-0.5,  0.5, -0.5}, { 0.0,  1.0,  0.0}
	},

	{
		{ 0.5, -0.5,  0.5}, { 0.5, -0.5, -0.5}, { 0.5,  0.5,  0.5}, { 1.0,  0.0,  0.0}
	},
	{
		{-0.5, -0.5, -0.5}, { 0.5, -0.5, -0.5}, {-0.5,  0.5, -0.5}, { 0.0,  0.0, -1.0}
	 }
};

int face[6][3][3] = {
	{
		{0, 0, 0}, {0, 1, 0}, {0, 0, 0}
	},
	{
		{0, 0, 1}, {0, 0, 0}, {1, 0, 0}
	},
	{
		{0, 0, 1}, {0, 1, 0}, {1, 0, 0}
	},
	{
		{1, 0, 1}, {0, 0, 0}, {1, 0, 1}
	},
	{
		{1, 0, 1}, {0, 1, 0}, {1, 0, 1}
	},
	{
		{1, 0, 1}, {1, 0, 1}, {1, 0, 1}
	}

};
int judgeFace(int ID, float x, float y) {
	return face[ID][(int)(3.f * y)][(int)(3.f * x)];
}
void ini()
{
	for (int i = 0; i < 6; i++)
	{
		for (int j = 0; j < 4; j++)
		{
			float x = cube[i][j][0];
			float y = cube[i][j][1];
			float z = cube[i][j][2];

			cube[i][j][0] = (sqrt(3) / 6.f + 0.5) * x - sqrt(3) / 3.f * y + (-0.5 + sqrt(3) / 6.f) * z;
			cube[i][j][1] = (sqrt(3) / 3.f) * x + (sqrt(3) / 3.f) * y + (sqrt(3) / 3.f) * z;
			cube[i][j][2] = (-0.5 + sqrt(3) / 6.f) * x + (-sqrt(3) / 3.f) * y + (sqrt(3) / 6.f + 0.5) * z;
		}
	}
}
void renderFrame()
{
	ini();
	double time = 0;
	while (1) {
		time = time + 0.01;
		float z_buffer[screen_height + 1][screen_width + 1];
		for (int i = 0; i <= screen_height; i++)
			for (int j = 0; j <= screen_width; j++)
				z_buffer[i][j] = -100;
		char output[screen_height + 1][screen_width + 1];
		memset(output, ' ', sizeof(output));

		for (int i = 0; i < 6; i++)
		{
			for (float u = 0.f; u < 1.f; u = u + 0.01)
				for (float v = 0.f; v < 1.f; v = v + 0.01)
				{
					float m_x = (cube[i][1][0] - cube[i][0][0]);
					float m_y = (cube[i][1][1] - cube[i][0][1]);
					float m_z = (cube[i][1][2] - cube[i][0][2]);

					float n_x = (cube[i][2][0] - cube[i][0][0]);
					float n_y = (cube[i][2][1] - cube[i][0][1]);
					float n_z = (cube[i][2][2] - cube[i][0][2]);


					float x = m_x * u + n_x * v + cube[i][0][0];
					float y = m_y * u + n_y * v + cube[i][0][1];
					float z = m_z * u + n_z * v + cube[i][0][2];

					float rotation_x = cos(time) * x - sin(time) * z;
					float rotation_y = y;
					float rotation_z = sin(time) * x + cos(time) * z;

					float normal_x = (cube[i][3][0]) * cos(time) - sin(time) * (cube[i][3][2]);
					float normal_y = cube[i][3][1];
					float normal_z = (cube[i][3][0]) * sin(time) + cos(time) * (cube[i][3][2]);

					int screen_x = (rotation_x / (1 - rotation_z / c) + 1.f) / 2 * screen_width;
					int screen_y = (rotation_y / (1 - rotation_z / c) + 1.f) / 2 * screen_height;
					float screen_z = rotation_z / (1 - rotation_z / c);

					float L = normal_z;
					if (L > 0) {
						if (z_buffer[screen_y][screen_x] < screen_z)
						{
							z_buffer[screen_y][screen_x] = screen_z;
							if (judgeFace(i, u, v) == 1)
							{
								float tempu = u - (float)((int)(u * 3.f)) * 1.f / 3.f;
								float tempv = v - (float)((int)(v * 3.f)) * 1.f / 3.f;
								if ((tempu - 1.f / 6.f) * (tempu - 1.f / 6.f) + (tempv - 1.f / 6.f) * (tempv - 1.f / 6.f) <= 1.f / 36.f)
								{
									L = 0;
								}
								else
									L = (L + 0.1) * sqrt(2);
							}
							else
								L = (L + 0.1) * sqrt(2);
							int luminance_index = L * 8;
							if (luminance_index > 11)
								luminance_index = 11;
							output[screen_y][screen_x] = ".,-~:;=!*#$@"[luminance_index];
						}
					}
					else
						if (z_buffer[screen_y][screen_x] < screen_z)
							z_buffer[screen_y][screen_x] = screen_z;
				}
		}
		for (int j = screen_height; j >= 0; j--) {
			for (int i = 0; i <= screen_width; i++) {
				putchar(output[j][i]);
			}
			putchar('\n');
		}
		sleep(15000);
		printf("\x1b[26A");
	}
}
int main()
{
	renderFrame();
	return 0;
}
